LEC 8: Mucosal Immunology and Immunological Memory

Question 1

Distribution of mucosal tissues

Answer 1

• lachrymal gland
• salivary gland
• mammary gland
• kidney
• urogenital tract (uterus, bladder, vagina)
• conjunctiva
• sinus
• GI tract (oral cavity, trachea, esophagus, lungs, stomach, pancreas, intestines)

Question 2

What protects epithelial surfaces?

Answer 2

Mucins

Question 3

What protects entry to gut and airway?

Answer 3

Waldeyer’s ring

Question 4

What are Peyer’s patches?

Answer 4

gut associated secondary lymphoid tissue

Question 5

The systemic and mucosal immune systems use ______ strategies

Answer 5

The systemic and mucosal immune systems use DIFFERENT strategies

Question 6

Inflammatory capacity is ______ in intestinal

Answer 6

reduced

Question 7

What are M cells specialized to do?

Answer 7

Transport microorganisms to GALT (gut associated lymphoid tissue)

take up intact microorganisms and particulate antigens from gut to lumen and transfer to Peyer’s patch

Question 8

Describe the role of M cells

Answer 8

• specialized to transport microorganisms to GALT
• don’t secrete digestive enzymes/mucus
• lack glycocalyx
• poor lysosome system

take up intact microorganisms and particulate antigens from gut to lumen and transfer to Peyer’s patch

Question 9

What are the roles of dendritic cells?

Answer 9

capture antigen from the gut lumen

Question 10

In healthy individuals, lamina propria is populated with what?

What is the collective purpose of the lamina propria?

Answer 10

effector leukocytes

collective purpose is to RESTRAIN microorganisms

Question 11

What are intraepithelia lymphocytes?

Answer 11

• IELs are distinctive type of CD8 T cells
• ~ one IEL for every 7-10 epithelial cells
• either αβ-CD8 or γδ-CD8
• TCRs with limited antigen specificities
  = have been activated by relatively
  small number of antigens

express integrin αEβ7 → binds to E-cadherin
= intercalate with epithelial cells AND
maintain barrier function

Question 12

Mucosally activated T and B cells home to the type of mucosa in which they were activated

Answer 12

express chemokine receptors CCR9
→ binds CCL25 secreted by
small intestine epithelium

express integrin α4β7
→ binds to MAdCAM-1 on
endothelial cells of blood vessels
in gut wall

induction of gut-homing receptors
and integrins is under control of
intestinal DCs

*relevance to vaccination strategies

Question 13

Secretory IgA can bind pathogens in
_______ locations.

What is IgA?

Answer 13

Secretory IgA can bind pathogens in
several locations

IgA = a non-inflammatory antibody that limits access of pathogens, commensals, and food products to mucosal surfaces

Question 14

Secretory IgA can bind pathogens in

several locations

Answer 14

1. Export toxins from lamina propria
2. Neutralize antigens in endosomes
3. Neutralize antigens in gut lumen
4. Bind pathogens on M-cell surface
5. Bind pathogens in Mcell endosome

Question 15

Bacterial proteases cleave IgA1

Compare IgA1 to IgA2.

Answer 15

IgA1
• 26 amino acids in hinge
• more flexible
• more susceptible to cleavage

IgA2
• 13 amino acids in hinge
• less flexible
• more resistant to cleavage

Question 16

Secretory antibodies become attached

to ______

Answer 16

Secretory antibodies become attached

to mucus

Question 17

Intestinal helminth infections provoke….

Answer 17

strong TH2-mediated immune responses

Question 18

Benefits of gut microbiota

Answer 18

synthesis of essential metabolites

breakdown plant fibers in food

inactivate toxic substances in food/made by pathogens

prevent pathogens from benefitting from the resources of the human gut

interact with epithelium to trigger development of secondary lymphoid tissue